224 Novel Ultrasound Dilution Technique Detects Left-To-Right Shunts with High Accuracy in Children

Abstract

Objectives: Recently introduced paediatric cardiac output monitor (COstatus, Transonic Systems Inc. Ithaca, NY) also measures blood volumes and detects cardiac shunts. The current study assessed its ability to identify left-to-right shunts and measured associated blood volumes during cardiac catheterisation in children. Patients and Methods: Cardiac catheterisation was performed in 20 children and adolescents (3.5 kg- 102 kg). Shunts and pulmonary (Qp) versus systemic blood flow (Qs) ratio were determined by routine oximetry. Subsequently three measurements with COstatus were performed while the monitor software announces the recognition of left-to-right shunt. Dilutions curves were recorded and validated. Results: Left-to-right shunts due to various types of cardiac defects were detected in 6 patients by oximetry. Applying COstatus diagnostic accuracy was very convincing, with a sensitivity of 100% (6/6) and a specificity of 92.8% (13/14). The threshold for determination a left-to-right shunt was an Qp/Qs ratio of 1.3. In one case of a hypertrophic obstructive cardiomyopathy the distortion of the dilution curve led to a false positive result. A significant difference was detected for means of central blood volume index between patients with left-to-right shunts and controls with no cardiac shunts (95% CI; 24.9 versus 18.2 ml/kg; P< 0.05). Conclusion: Novel ultrasound dilution technique identifies left-to-right shunts in children with a high sensitivity and detects even small shunts with an Qp/Qs ratio of 1.3. Raised central blood volume index corresponds well with clinical features in patients with left-to-right shunts and may become helpful a diagnostic parameter in the future.